When an air-fuel mixture is combusted in an engine combustion chamber, a small portion of the combusted gas may enter the engine crankcase through the piston rings. This gas is referred to as blow-by gas. To prevent this untreated gas from being directly vented into the atmosphere, a crankcase ventilation system is provided between the higher pressure crankcase and the lower pressure intake manifold to allow the blow-by gas to flow from the crankcase into the intake manifold and be mixed with fresh air. From here, the gas may be re-inducted into the combustion chamber for re-combustion.
Engine lubrication oil used to lubricate moving parts of the engine is present in the crankcase during normal engine operation. The high pressure in the crankcase causes some of the lubricating oil to be suspended in a mist form. This oil mist can then mix with the blow-by gas and be returned to the intake manifold for combustion via a communication passage. However, combustion of the oil may cause the net oil consumption to increase, as well as degrade engine emission quality. To address these issues, oil separators have been developed to separate the oil content from the blow-by gas containing the oil mist. After separation, the oil is returned to the engine lubricating system while the blow-by gas is returned to the engine intake system. An oil separator may be formed within a cam cover by positioning an oil baffle within the cam cover and form an oil separation chamber therein. The blow-by gas containing the oil mist, i.e. blow-by vapors, may be passed though the oil separation chamber.
However, one potential problem with cam covers and oil baffles is that they may be contributors to the overall noise radiated by an internal combustion engine during operation. Also it is becoming more common to include composite materials, including composites that include plastics, in internal combustion engines. However, this increases the challenge of reducing engine noise because benchmarking and experience indicate that isolated cam covers made of composite materials may be noisier than isolated cam covers made of metallic materials.
One approach to create a plastic rocker cover defining an oil-gas separating chamber is disclosed by Sato et al. in U.S. Pat. No. 4,323,745. Sato et al. disclose a rocker cover with an outer cover, and an inner partition member disposed inside the outer cover forming a gas separation chamber. Downward and upward barrier-like projections are arranged in line and in intervals in the direction of flow of the blow-by gases. The projections form a zig-zag shaped blow-by gas passage for promoting separation of oil from blow-by gases. The outer cover member has a buffer wall in the form of a rectangular ring or tube disposed inside of the peripheral wall thereof. The partition member is secured to a lower free end of the buffer wall. However, the inventors have recognized several issues with such an oil separator. As one example, the inner partition member may lack sufficient rigidity to avoid significant vibration, and the way the outer cover member and the inner partition member are secured to one another may also contribute to excess vibration between the outer cover member and the inner partition member.
Thus in one example, the above issues may be addressed by a system for an internal combustion engine. The system may include a cam cover configured to be mounted on a cylinder head. The system may also include an oil baffle that may have a generally planar body with a first face and a second face opposite the first face. The first face may be coupled to the cam cover and may define an oil separation chamber between the cam cover and the first face. The oil baffle may include one or more stiffening members coupled to and extending from and substantially normal to the second face.
In this way various example valve covers in accordance with the present disclosure may have a high structural rigidity. In addition, various example valve covers in accordance with the present disclosure may include an attachment pattern connecting the cam cover to the oil baffle that may add to its effectiveness in reducing cover surface vibration and cover radiated noise.
In this way, the amount of noise and vibration that may be radiated by the valve cover may be greatly reduced. In addition, manufacturing costs may be reduced by molding the whole baffle arrangement using a single mold. And, in another example in which the separator is configured to enable oil separated at the baffles to drip directly onto the camshaft or onto cam caps, the need for oil drain valves and/or oil drain paths may be averted or reduced, thereby allowing the separator to work more efficiently within the spatial constraints.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.